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A 58-year-old man with no history of heart disease presented to the emergency department having experienced 1 hour of progressive chest pain. His heart rate was 80 bpm and his blood pressure was 176/92 mm Hg; the results of the physical examination were otherwise unremarkable. The administration of sublingual nitroglycerine caused a precipitous drop in his blood pressure to 90/50 mm Hg. A 12-lead ECG showed a 1-mm ST-segment elevation in leads III, aVF, and V1 (Figure 1A). The placement of right-sided precordial leads revealed a 2-mm ST-segment elevation in lead V4R (Figure 1B). Emergency coronary arteriography demonstrated a left dominant coronary circulation with nonobstructive disease in the left anterior descending coronary artery and the posterior descending branch of the left circumflex coronary artery and a total occlusion of the proximal right coronary artery distal to the conus branch (Figure 2A). The nondominant right coronary artery occlusion was managed with balloon dilation and stenting (2.25 mm×15.0 mm stent), resulting in the immediate resolution of chest pain and ST-segment elevation (Figure 2B). The peak creatine kinase-MB level was 10.1 ng/mL, and the peak troponin T level was 0.37 ng/mL. Subsequent echocardiography was normal, and the patient recovered without sequelae. Clinically recognized right ventricular myocardial infarction resulting from a nondominant right coronary artery is rare. Previous reports indicate that ECG changes may be less dramatic than those that were observed in our patient.

Figure 2. A, Initial right coronary arteriogram shows total occlusion distal to the origin of the conus branch. B, Right coronary arteriogram after balloon dilation and stent placement reveals a nondominant artery that gives rise to a right ventricular acute marginal branch.